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Three-dimensional structure of an old-growth Pseudotsuga-tsuga canopy and its implications for radiation balance, microclimate, and gas exchange

Publication ,  Journal Article
Parker, GG; Harmon, ME; Lefsky, MA; Chen, J; Van Pelt, R; Weiss, SB; Thomas, SC; Winner, WE; Shaw, DC; Franklin, JF
Published in: Ecosystems
January 1, 2004

We describe the three-dimensional structure of an old-growth Douglas-fir/western hemlock forest in the central Cascades of southern Washington, USA. We concentrate on the vertical distribution of foliage, crowns, external surface area, wood biomass, and several components of canopy volume. In addition, we estimate the spatial variation of some aspects of structure, including the topography of the outer surface, and of microclimate, including the within-canopy transmittance of photosynthetically active radiation (PAR). The crowns of large stems, especially of Douglas-fir, dominate the structure and many aspects of spatial variation. The mean vertical profile of canopy surfaces, estimated by five methods, generally showed a single maximum in the lower to middle third of the canopy, although the height of that maximum varied by method. The stand leaf area index was around 9 m2 m-2, but also varied according to method (from 6.3 to 12.3). Because of the deep narrow crowns and numerous gaps, the outer canopy surface is extremely complex, with a surface area more than 12 times that of the ground below. The large volume included below the outer canopy surface is very porous, with spaces of several qualitatively distinct environments. Our measurements are consistent with emerging concepts about the structure of old-growth forests, where a high degree of complexity is generated by diverse structural features. These structural characteristics have implications for various ecosystem functions. The height and large volume of the stand indicate a large storage component for microclimatic variables. The high biomass influences the dynamics of those variables, retarding rates of change. The complexity of the canopy outer surface influences radiation balance, particularly in reducing short-wave reflectance. The bottom-heaviness of the foliage profile indicates much radiation absorption and gas exchange activity in the lower canopy. The high porosity contributes to flat gradients of most microclimate variables. Most stand respiration occurs within the canopy and is distributed over a broad vertical range.

Duke Scholars

Published In

Ecosystems

DOI

ISSN

1432-9840

Publication Date

January 1, 2004

Volume

7

Issue

5

Start / End Page

440 / 453

Related Subject Headings

  • Ecology
  • 3109 Zoology
  • 06 Biological Sciences
  • 05 Environmental Sciences
 

Citation

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ICMJE
MLA
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Parker, G. G., Harmon, M. E., Lefsky, M. A., Chen, J., Van Pelt, R., Weiss, S. B., … Franklin, J. F. (2004). Three-dimensional structure of an old-growth Pseudotsuga-tsuga canopy and its implications for radiation balance, microclimate, and gas exchange. Ecosystems, 7(5), 440–453. https://doi.org/10.1007/s10021-004-0136-5
Parker, G. G., M. E. Harmon, M. A. Lefsky, J. Chen, R. Van Pelt, S. B. Weiss, S. C. Thomas, W. E. Winner, D. C. Shaw, and J. F. Franklin. “Three-dimensional structure of an old-growth Pseudotsuga-tsuga canopy and its implications for radiation balance, microclimate, and gas exchange.” Ecosystems 7, no. 5 (January 1, 2004): 440–53. https://doi.org/10.1007/s10021-004-0136-5.
Parker GG, Harmon ME, Lefsky MA, Chen J, Van Pelt R, Weiss SB, et al. Three-dimensional structure of an old-growth Pseudotsuga-tsuga canopy and its implications for radiation balance, microclimate, and gas exchange. Ecosystems. 2004 Jan 1;7(5):440–53.
Parker, G. G., et al. “Three-dimensional structure of an old-growth Pseudotsuga-tsuga canopy and its implications for radiation balance, microclimate, and gas exchange.” Ecosystems, vol. 7, no. 5, Jan. 2004, pp. 440–53. Scopus, doi:10.1007/s10021-004-0136-5.
Parker GG, Harmon ME, Lefsky MA, Chen J, Van Pelt R, Weiss SB, Thomas SC, Winner WE, Shaw DC, Franklin JF. Three-dimensional structure of an old-growth Pseudotsuga-tsuga canopy and its implications for radiation balance, microclimate, and gas exchange. Ecosystems. 2004 Jan 1;7(5):440–453.
Journal cover image

Published In

Ecosystems

DOI

ISSN

1432-9840

Publication Date

January 1, 2004

Volume

7

Issue

5

Start / End Page

440 / 453

Related Subject Headings

  • Ecology
  • 3109 Zoology
  • 06 Biological Sciences
  • 05 Environmental Sciences